Assessment of activated porous granules on implant fixation and early bone formation in sheep

Titanium Nanobowl-Based Nest-Like Nanofiber Structure Prepared at Room Temperature and Pressure Promotes Osseointegration of Beagle Implants

Nest-like nanofiber structures have potential applications in surface modifications of titanium implants. In this study, nest-like nanofiber structures were prepared on a titanium surface at room temperature and pressure by using the nanobowl template-assisted method combined with alkali etching. The characterization and biocompatibility of this material were analyzed by cellular adhesion, death, CCK-8, ALP, and RT-PCR assays in vitro, and osseointegration was evaluated by micro-CT and fluorescent labeling in vivo. The results showed that this nest-like nanofiber structure has a firmer and asperate surface than nanotubes, which leads to better cellular adhesion, proliferation, and differentiation capacity. In a beagle alveolar bone implant model, the nest-like nanofiber structure showed a better osseointegration capacity. In conclusion, this nest-like nanofiber structure has potential applications in dental implantology.

Efficacy of marine bioactive compound fucoidan for bone regeneration and implant fixation in sheep

The need for a substitute for allograft and autograft is rising as bone graft surgeries exceed available supplies. We investigated the efficacy of the low-molecular weight marine bioactive compound fucoidan (FUC) on bone regeneration and implant fixation in seven female sheep, as FUC has shown great promise as a bone substitute. Titanium implants were inserted bilaterally in the distal femurs to test three hydroxyapatite/fucoidan (HA/FUC) groups and compared to allograft. The HA was coated with either 500 or 1500 μg of FUC, obtained by microwave-assisted chemical extraction, or 500 μg of FUC obtained by an enzyme-assisted extraction method. The concentric 2-mm gap around the implant was filled with either one of the HA/FUCs or allograft from the donor sheep. After 12 weeks, implant-bone blocks were harvested and divided into three parts for mechanical push-out testing, immunohistochemistry, and micro-CT and histomorphometry. Pronounced bone formations were observed by micro-CT and histomorphometry in all groups, but higher bone volume fractions were seen in the allograft group compared to the three HA/FUC groups. The trabecular thickness, trabecular separation, and architectural anisotropy were all significantly higher in the allograft group compared to the three HA/FUC groups. In conclusion, adequate bone formation was observed in all groups, although the bone formation was significantly greater in the allograft group. Also, no significant differences existed in the shear mechanical properties between groups, suggesting that the combination of HA and FUC can achieve a similar fixation strength to allograft in this model.

Role of Special AT-Rich Sequence-Binding Protein 2 in the Osteogenesis of Human Dental Mesenchymal Stem Cells

Dental mesenchymal stem cells (MSCs) are recognized as a critical factor in repair of defective craniofacial bone owing to the multiple differentiation potential, the ability to regenerate distinct tissues, and the advantage that they can be easily obtained by relatively noninvasive procedures. Special AT-rich sequence-binding protein 2 (SATB2) is a nuclear matrix protein, involved in chromatin remodeling and transcriptional regulation, and has been reported to be as a positive regulator of osteoblast differentiation, bone formation, and bone regeneration in MSCs. In this study, we systematically investigated the capability of SATB2 to promote the osteogenic differentiation of periodontal ligament stem cells (PDLSCs), dental pulp stem cells (DPSCs), and stem cells from human exfoliated deciduous teeth (SHED). RNA-seq analysis and quantitative real-time PCR (RT-PCR) revealed that genes regulating osteogenic differentiation were differentially expressed among three cell types and SATB2 was found to be expressed at a relatively high level. When the three cell types overexpressed SATB2 with AdSATB2 infection, alkaline phosphatase (ALP) staining, ALP activity, Alizarin Red S staining, and quantification tended to increase with an increasing infection rate. It showed opposite results after infection with AdsiSATB2. RNA-seq analysis indicated that the expression of downstream osteogenic genes was affected by AdSATB2 infection and quantitative RT-PCR confirmed that nine osteogenic genes (Spp1, Sema7a, Atf4, Ibsp, Col1a1, Sp7, Igfbp3, Dlx3, and Alpl) were upregulated, to various extents, following SATB2 overexpression. In addition, quantitative PCR results indicated that SATB2 affected the expression of MSC markers. These results suggested an important role of SATB2 in the osteogenesis of PDLSCs, DPSCs, and SHED. Further research is warranted to investigate SATB2-mediated regulation of osteogenic differentiation and to evaluate the therapeutic use of SATB2 for the regeneration of defective craniofacial bone tissue.

Biofunctionalization with a TGFβ-1 Inhibitor Peptide in the Osseointegration of Synthetic Bone Grafts: An In Vivo Study in Beagle Dogs

Objectives: The aim of this research was to determine the osseointegration of two presentations of biphasic calcium phosphate (BCP) biomaterial—one untreated and another submitted to biofunctionalization with a TGF-β1 inhibitor peptide, P144, on dental alveolus. Materials and Methods: A synthetic bone graft was used, namely, (i) Maxresorb^® (Botiss Klockner) (n = 12), and (ii) Maxresorb^® (Botiss Klockner) biofunctionalized with P144 peptide (n = 12). Both bone grafts were implanted in the two hemimandibles of six beagle dogs in the same surgical time, immediately after tooth extraction. Two dogs were sacrificed 2, 4, and 8 weeks post implant insertion, respectively. The samples were submitted to histomorphometrical and histological analyses. For each sample, we quantified the new bone growth and the new bone formed around the biomaterial’s granules. After optical microscopic histological evaluation, selected samples were studied using backscattered scanning electron microscopy (BS-SEM). Results: The biofunctionalization of the biomaterial’s granules maintains a stable membranous bone formation throughout the experiment timeline, benefitting from the constant presence of vascular structures in the alveolar space, in a more active manner that in the control samples. Better results in the experimental groups were proven both by quantitative and qualitative analysis. Conclusions: Synthetic bone graft biofunctionalization results in slightly better quantitative parameters of the implant’s osseointegration. The qualitative histological and ultramicroscopic analysis shows that biofunctionalization may shorten the healing period of dental biomaterials.

Micro-CT - a digital 3D microstructural voyage into scaffolds: a systematic review of the reported methods and results

BACKGROUND

Cell behavior is the key to tissue regeneration. Given the fact that most of the cells used in tissue engineering are anchorage-dependent, their behavior including adhesion, growth, migration, matrix synthesis, and differentiation is related to the design of the scaffolds. Thus, characterization of the scaffolds is highly required. Micro-computed tomography (micro-CT) provides a powerful platform to analyze, visualize, and explore any portion of interest in the scaffold in a 3D fashion without cutting or destroying it with the benefit of almost no sample preparation need.

MAIN BODY

This review highlights the relationship between the scaffold microstructure and cell behavior, and provides the basics of the micro-CT method. In this work, we also analyzed the original papers that were published in 2016 through a systematic search to address the need for specific improvements in the methods section of the papers including the amount of provided information from the obtained results.

CONCLUSION

Micro-CT offers a unique microstructural analysis of biomaterials, notwithstanding the associated challenges and limitations. Future studies that will include micro-CT characterization of scaffolds should report the important details of the method, and the derived quantitative and qualitative information can be maximized.